E-Bike Power Module Axial Layout for Compact Torque Sensing
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Solution Overview
Problem
Conventional power modules for electric assisted bicycles face challenges in size reduction due to radial arrangement of the motor and reducer, leading to increased radial thickness, and suffer from inaccurate pedaling torque measurement due to the torque sensor's position configuration, which only senses one pedal force.
Innovation Solution
The motor and reducer are arranged axially within the power module, with the stator and fixed gear fixed to opposite sides of a partition portion, optimizing space utilization and allowing for accurate pedaling torque measurement by serially connecting the torque sensor in the torque transmission path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the motor and reducer are radially arranged and sleeved around a central pedal shaft, then the power module can be compact in axial direction, but the radial thickness is increased
Solution Approach 1:
The patent transitions from a radial arrangement (motor and reducer sleeved around the pedal shaft in the radial direction) to an axial arrangement where the motor and reducer are positioned along the axial direction. This dimensional change allows the components to be stacked axially rather than radially, reducing the radial thickness while maintaining compact axial length.
2Device complexity
If the torque sensor is disposed between the housing and pedal-shaft two-way bearing, then the power module structure is simplified, but the pedaling torque measurement accuracy is reduced
Solution Approach 1:
The patent introduces a torque transmission component (such as a gear or sprocket) as an intermediary element between the pedal shaft and the torque sensor. This intermediary allows the torque sensor to be positioned in series within the torque transmission path, enabling accurate measurement of pedaling torque while maintaining a relatively simple overall structure.
3Device complexity
If the torque sensor is not serially connected within the torque transmission path, then the power module design is simplified, but the sensing error is increased
Solution Approach 1:
The patent positions the torque sensor in series within the torque transmission path, creating a feedback mechanism where the sensor directly measures the torque being transmitted through the pedal shaft. This serial connection ensures that the torque sensor captures accurate pedaling torque data, reducing sensing errors while maintaining reasonable design complexity.
Data Source
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AI summary
A power module (1, 1a, 1b, 1c) of an electric assisted bicycle is disclosed and includes a pedal shaft (10), a housing (20), a motor (30), a reducer (40) and a gear-plate output shaft (50) and a sensing component (60). The housing (20) includes a partition portion (24) extended along a radial direction to divide an inner space of the housing (20) into a motor accommodation portion (201) and a reducer accommodation portion (202) for accommodating the motor (30) and the reducer (40), respectively. A stator (31) of the motor (30) and a fixed gear (43) are respectively fixed to a first side (S1) and a second side (S2), which are two opposite sides of the partition portion (24). A reducer input shaft (41) includes two ends connected to the motor (30) and the reducer (40), respectively, and an input-shaft main part (411) disposed therebetween is connected to a third side (S3) of the partition portion (24). With the connection configuration of the three sides (S1, S2, S3) of the partition portion (24), the space utilization of the entire power module (1, 1a, 1b, 1c) is optimized.